Hi Jerome & Bas!
Yes, it's not a F18 but a Hobie 18. These came in several different versions though. By the looks of the daggerboard cases (shorter for narrower daggers, i.e. higher aspect ratio compared to standard Hobie 18) it looks as if it could be a Hobie 18
Formula (not to be mixed up with the Hobie F18 (Tiger & Wildcat).
The Hobie 18 Formula was produced by Hobie Europe based in France. As you are based in Belgium the posssibility is not slim that that's what you got. I got one myself. Some signs that can guide you (except from the narrower dagger cases) are a longer mast compared to a standard Hobie 18 and radial cut mainsail out of mylar. There should also be a riveted manufacturing plate at one of the crossbars (can't remember which one...) that says Hobie Europe, Touloun, France or something similar. You can also compare the parts diagram located in the product support pages on
http://www.hobiecat.com/xe/en/support/hobie-18/ (these are for the US made versions of the Hobie 18's) and compare these with this one of a Hobie 18 Formula
http://www.hobie-cat.net/download/part_guides/hc18.pdfAs a side note, an easy way (amongst several other differences) to differentiate the F18's from the earlier Hobie 18's is the fact that all F18's have strate crossbars whereas the Hobie 18's in all of their different versions have konvex ones (arched upwards).
Hope you get your cat sorted out to go saililng!
Brgds from a chilly Gothenburg in Sweden